Instant Runoff Voting (IRV)

Instant runoff voting is a type of ranked-choice voting that is most often used for electing a single candidate.

Instant runoff voting is similar to a traditional runoff election, but better. With a traditional runoff system, a first election has multiple candidates, and if no candidate receives a majority of the vote, a second or runoff election is held between the top two candidates of the first election. A traditional runoff election prevents a candidate from winning with less than a majority of the votes.

With IRV, a voter ranks the candidates in order of preference, and the votes are assigned to the top ranked candidate on each ballot. The candidate with the fewest votes is eliminated and those votes are transferred to their second choices. This process is repeated until a candidate has a majority or only two candidates remain.

IRV is better than a traditional runoff for two reasons. First, voters only have to vote once. Holding an election is an expensive and time-consuming process so having one election is much better than two. Second, with IRV, losing candidates are eliminated one by one instead of eliminating all but the top two at once. This helps ensure that the best candidates are progressing at each round (e.g., if the second and third place candidates are close to each other).

You can see an example of IRV results generated by OpaVote.

IRV is used for government elections in Minneaoplis, Minnesota; Berkeley, Oakland, San Francisco, and San Leandro in California; and Takoma Park, Maryland; Australia; and Ireland.

OpaVote provides a few versions of IRV. A general version of IRV (with some counting options if you are using a Count), the version of IRV used in San Francisco, and the version of IRV used in Oakland County. The differences between the three versions are small and you can see the details in our Help documentation.

Instant Runoff Voting

The general version of IRV has several options (but note that these options are available only for counts and not for elections and polls). By default, IRV uses the following options:

  • Zero for Candidate Elimination
  • Backward for Tie Breaking
  • Skip for Remove Overvotes
  • Skip for Remove Undervotes

San Francisco RCV

The city of San Francisco uses the San Francisco RCV rules for city elections. San Francisco enacted IRV in 2002, its first election with IRV was in 2004, and it has been used annually since then.

The differences with the general method are the following options:

  • Losers for Candidate Elimination
  • Random for Tie Breaking
  • Stop for Remove Overvotes
  • Skip for Remove Undervotes

Oakland RCV

This method implements IRV as used by the cities of Oakland, San Leandro, and Berkeley. Oakland approved use of IRV in 2006, and San Leandro and Berkeley approved use of IRV in 2010. All three cities had their first IRV elections in 2010.

The differences with the general method are the following options:

  • Zero for Candidate Elimination
  • Random for Tie Breaking
  • Stop for Remove Overvotes
  • Skip for Remove Undervotes